Bladder Cancer-Obesity Link Confirmed

For every 5 kg/m2 increase in BMI, the risk of bladder cancer rose 4.2%.

Preobese and obese individuals had a 7% and 10% increased risk of bladder cancer, respectively.

A new systematic review and meta-analysis confirms an association between obesity and bladder cancer. Pre-obese individuals also may be at risk.

For the meta-analysis, Yong-Bing Xiang, MD, and colleagues from the Shanghai Cancer Institute at Renji Hospital in China, pooled results from 15 cohort studies published by September 2014 from North America, Europe (including Scandinavia), Asia, and Australia. Among 14 million people, 38,072 bladder cancer cases were identified.

Researchers observed a linear relationship between body mass index (BMI) and bladder cancer risk. For each 5 kg/m2 increase in BMI, there was a 4.2% hike in bladder cancer risk.

The findings update and expand a 2013 meta-analysis that reached a similar conclusion. A shortcoming of that study was it did not address confounders.

Investigators in the current study adjusted for smoking and found no meaningful differences. They also examined other possible confounders. Studies that adjusted for physical activity, alcohol consumption, and family history of cancer, for example, actually showed stronger associations.

Given the rising rates of pre-obesity and obesity worldwide, “more in-depth studies are warranted to disentangle the roles of the biological mechanisms involved in obesity-related carcinogenesis,” the researchers concluded.